I am facing a problem in inserting a date type data into the database that is having a russian characterset enabled. I am having an application that works fine in English and now I want to enter russian data in place of English data into the database.

The application shows ORA-01858 error that is due to invalid date format. I have installed the database with NLS_LANG setting as RUSSIAN_CIS.CL8MSWIN1251 and also the forms to support russian with same settings.

If Forms is used with American_america.WE8MSWIN1252 and database is used in Russian settings and both are not on the same server then they work fine. If they are on same server whether forms in russian or american settings it gives the above error .

Pls. revert back ASAP.. Once this issue is solved we are all set to go live.

if your DB has been created with CL8MSWIN1251 codepage then you have to set any *CL8* codepage on client (forms).
If you run on Windows then you can use RUSSIAN_CIS.CL8MSWIN1251 locally and remotely.
In RUSSIAN_CIS.CL8MSWIN1251 RUSSIAN means messages will be returned in Russian. CIS means that dates, currency, sorting will be done by russian CIS standards. CL8 means cyrillic codepage family. MSWIN1251 means Windows cyrillic codepage.
TNS will transparently translate CL8MSWIN1251 to any other CL8 codepage, i.e. CL8ISO8859P5.
If you do not need CIS date format you can set RUSSIAN_AMERICA.CL8MSWIN1251 on client. In this case you will have to enter dates in US format.

PS/ to check database codepages and other NLS values
SELECT * FROM sys.props$ WHERE name like 'NLS%';